Remote control vehicles, and particularly remote control motorcycles are well known. Typically, a remote control motorcycle includes a chassis supported along a longitudinal axis by front and rear wheels, and the front wheel is a castering wheel having a fixed castering axis. One aspect of this invention relates to steering remote control motorcycles of this type.
U.S. Pat. No. 4,342,175 entitled "Radio Controlled Motorcycle," issued to Cernansky et al., describes a toy motorcycle which uses a shifting center of gravity to cause the motorcycle to lean to the left or to the right. The front wheel then "casters" or turns in the direction in which the motorcycle is leaning, thereby to turn in that direction. Applicants own U.S. Pat. No. 5,368,516 entitled "Radio-Controlled Two-Wheeled Toy Motorcycle" which describes a remote control motorcycle which uses a somewhat similar steering mechanism as the Cernansky design. However, in applicant's U.S. Pat. No. 5,368,516, the structure used for affecting the weight shift to initiate the turn differs somewhat to allow a more responsive turn.
Thus, these patents disclose a method of steering which involves a weight swing to the right or the left, such as by moving the batteries and the motor, etc., to displace the center of gravity of the motorcycle. The displacement of the center of gravity causes the motorcycle to turn in the direction of the displacement. When the displaced weight returns again to the centerline, i.e., along the longitudinal axis of the motorcycle, the force of the front wheel upon the castering axis causes the forward wheel to "castor" back to an in-line position, i.e., in-line with the longitudinal axis of the motorcycle.
A primary drawback with "gravity shift" steering mechanisms of this type is that they generally require a relatively large turning radius to turn the forward wheel about the castering axis. Also, motorcycles which use this steering mechanism must, by necessity, allow the forward or front wheel to castor in either direction in response to weight shifts of the rest of the motorcycle. That is, the front wheel must always be able to freely rotate in either direction in order to initiate a turn, but there is no control over this rotation of the castering wheel. For instance, if the front wheel of the vehicle were to encounter a bump along its path or uneven terrain, the castering wheel would respond by rotating the front wheel in the direction of least resistance.
More recent remote control motorcycles use a principle referred to as "counter-steering" to affect turning of the vehicle. For instance, U.S. Pat. No. 5,709,583 assigned to Tyco Industries, Inc. discloses a remote control motorcycle which using the counter-steering principle for turning. More specifically, this patent discloses a motorcycle which uses a servo operated spring force to turn the front wheel about its steering axis toward either the right or the left. Furthermore, if the applied spring force initially turns the front wheel to the left, the bike will then lean, or fall, to the right, in the opposite direction. This lean initiates a right turn because the weight of the bike leaning to the right initially forces the front wheel to straighten, i.e., rotate into the turn, as the gravity force of the motorcycle overcomes the applied spring force. The front wheel continues to rotate until it is turned to the right, thereby establishing a right turn. The spring force remains applied to the front wheel throughout the turn, and removal of the spring force causes the motorcycle to resume a straight path, with the front wheel in alignment with the longitudinal axis of the motorcycle.
U.S. Pat. No. 5,820,439, assigned to Shoot the Moon Products, Inc., describes another motorcycle which also uses the counter-steering principle. Instead of a servo/spring system, the motorcycle of the '439 patent uses a motor and a clutch to exert the counter-steering force. This motorcycle also includes a gyroscopic flywheel mounted between the two wheels and operatively connected to the clutch which the '439 claims assists the stability of the motorcycle at slow speeds and reduces wobble of the front wheel on rough terrain.
While these two more recent remote control vehicles seem to represent an improvement over the prior art motorcycles which used gravity shifting steering, applicants believe there is still room for further improvement. More specifically, these vehicles have not proved to be suitable for rugged terrain. Moreover, the turning capability is somewhat limited.
It is an object of the present invention to improve upon the stability of a remote control toy vehicle, particularly a motorcycle.
It is a further object of the present invention to enhance the compatibility of a remote control motorcycle for off-road use, on a wide variety of terrains.
It is another object of the present invention to improve steering versatility of a remote control motorcycle.